1. Field of the Invention
The invention relates to a cooling device for electrical power units of electrically operated vehicles, wherein the power unit has a power section and a control section.
2. Description of the Related Art
It is generally known to equip vehicles with electrical traction drives. DE 37 28 171 C2 U.S. Pat. No. 4,998,591 discloses, for example, an electromechanical drive system for a full-track vehicle. At least one electric traction motor and an electric steering motor are provided and can be used to mechanically transmit the regenerative steering power from one drive side to the other.
EP 1 060 941 B1 discloses a device for controlling and operating an electrical vehicle drive. In this drive arrangement, each drive side is provided with its own electric drive motor.
In order to supply electrical power to the electric motors for driving such vehicles, current generators—which are driven by internal combustion engines—are generally provided. The electrical power is transmitted to the electric motors via corresponding power units. Such power units comprise a power section and a control section which are combined to form a compact physical unit. Depending on the transmitted power, the power units heat up and have to be cooled in order to protect their components from overheating. Powers which are transmitted in the power sections are 1 to 4 powers of ten (10 to 104) greater than in the control sections.
The single loop cooling systems used have to be designed for the lower maximum permissible temperatures of the control electronics. Therefore, large heat exchangers containing correspondingly large amounts of coolant are required in order to be able to dissipate the large amount of heat which is produced in the power sections using the low cooling power of such a low temperature cooling arrangement.